Conventional DR sensors, such as solid-state based flat panel detectors (FPDs), are well known for their advantages over traditional screen/film (S/F) cassettes. DR sensors are the current state of the art for medical and security imaging as these provide substantial advantages over traditional analog S/F based systems. Not only does digital radiography offer higher resolution and higher quality images, but it also permits substantially instant acquisition and analysis of captured images. Conventional DR sensors require cable connections at least for voltage supply, transmission of control signals, and transfer of image data. Cable connections, however, are not only an inconvenience for examining bed-bound patients, but also can hinder the use of DR sensors in sterile environments, such as trauma centers and operating rooms. To overcome the constraints presented by wired DR sensors, numerous implementations of wireless DR sensors have been proposed.
Patent Application Publication US 2002/0150214 A1 entitled “X-ray installation with wireless communication between the radiation receiver and control unit”, by Martin Sphan (herein “Sphan”), discloses a transportable radiation receiver that communicates via a wireless communication link with a control device of the mobile imaging unit. Transmission and reception units for a bidirectional communication are provided at the radiation receiver and at the control device, respectively. According to Sphan, any optical or radio frequency (RF) communication technique may be suitable for fast transmission of relevant signals between the transmission and reception units, while allowing positioning freedom of the radiation receiver. Sphan does not consider any problems that are usually caused by free positioning of the radiation receiver.
U.S. Pat. No. 7,567,651 B2 entitled “directional antenna system for wireless x-ray devices” to Serceki et al., (herein “Serceki”), discloses a directional antenna system that employs a wireless link between an x-ray detector and an x-ray tube. Specifically, Serceki identifies that one problem with conventional x-ray systems is improper patient positioning which prevents the radiologist or technician from successfully imaging desired areas. Serceki also identifies that improper patient placement can create passive interference which will affect the wireless signals traveling between a transmitter and a receiver. To address these issues, Serceki discloses embodiments of an x-ray system in which directional antennas are positioned on both ends of the x-ray tube and at the x-ray detector. Specifically, the x-ray detector has one antenna that can communicate with the two antennas of the x-ray tube. The object of Serceki's invention is to assist with the proper placement and positioning of a patient for a targeted radiology session. It should be noted that in Serceki's patent, directional antennas at the x-ray tube and at the x-ray detector, located at positions where the patient would not block or interfere with the directionality of the antennas, are used to assist with the targeted placement and positioning of the patient. However, in mobile environments, for example, when examining bed-bound patients, it is very difficult to place the patient at a position where an antenna is not blocked or interfered by the patient.
U.S. Pat. No. 7,873,145 B2 entitled “Wireless Digital Image Detector” to Liu et al., (herein “Liu”) discloses a digital detector that includes a plurality of antennas. The digital detector transmits image data via one or more antennas to a mobile x-ray unit that also includes one or more antennas. Liu recognizes that the distance between antennas of the detector and antennas of the mobile x-ray unit may vary due to movement of the detector. Liu also recognizes that phase and intensity of communication signals between antennas may also vary as a result of movement. However, Liu neither disclose what the distance constraints are, nor does it offer a specific solution to the problems caused by the change in distance and movement of the detector.
Thus, although wireless communication between a DR sensor and a remote device is known, one of the main problems that a wireless medical imaging system faces is interference, either passive created by a physical obstacle, or active created by another signal source. A wireless system in use at a medical facility must contend with a large number of physical obstacles and active sources of interference. For example, when a bed-bound patient cannot be moved, it is necessary to bring the medical radiography equipment to the patient and locate the DR sensor in positions where data transmission may be hindered. Likewise, in the case of certain traumas being treated in an emergency room (ER) or an operating room (OR), it is not always possible to position the patient appropriately in order to orientate the DR sensor in direct line-of-sight (LoS) with the mobile unit. In addition, in the context of the above-described problems afflicting the implementation of wireless mobile radiographic imaging, it should be noted that wireless medical imaging applications generate very large amounts of data (up to hundreds of megabytes per image in some cases). Thus, to ensure fast and accurate transfer of medical image data from a DR sensor to a remote location, reliable and high speed data links are required. However, wireless medical imaging applications must compete with numerous other wireless medical devices and networks. Some wireless medical devices transmit relatively small amounts of data, but are life-supporting and life-saving applications that deliver critical care to a patient. However, current wired and wireless networks lack the level of security, privacy and bandwidth required for handling the amounts of medical data being generated in current wireless medical environments. Accordingly, reliable wireless medical devices capable of low power consumption and low emission of RF radiation are required.
The present invention has been made in an effort to address the above-described problems.